1. Field of the Invention
Embodiments of the disclosure are directed to optimizing routing and wavelength assignment in network.
2. Description of the Related Art
On a pure IP network, if a route becomes unavailable, packets can be forwarded along other routes to the same destination. This mechanism allows packets to be serviced before the topology change is advertised throughout the network.
To avoid IP lookup, Multi-Protocol Label Switching Traffic Engineering (“MPLS-TE”) can carry extra information, such as a label. Packets can be forwarded using label-based lookups. MPLS-TE allows the source to make routing decisions. The ingress can attach a label to an IP packet and let intermediate routers make forwarding decisions.
Present MPLS-based traffic engineered transport services deployed in the industry mostly uses policy-based re-optimization of tunnels that is either triggered by Interior Gateway Protocol (“IGP”)-TE advertisements of TE link resources or a periodic timer expiry based. This re-optimization can be achieved via constrained path re-computation and tunnel reroute along the new path using “make-before-break” method. The policy constrained tunnel paths may optimize the individual tunnel's resource goals. Tunnel flapping, or frequent re-routing, due to conflicting impact of multiple different reroute policies applied across different parts of the network may not be monitored and therefore not prevented.
In the traffic engineered networks, the MPLS/GMPLS tunnels are often re-optimized under policy control to meet the traffic engineering goals of tunneling services and also to optimally utilize the traffic engineering resources of the network topology. However policy controlled re-optimization involve re-routing of tunnels across parts of the network, as determined by the policy constrained path computation.
The policy constrained tunnel paths may optimize the individual tunnel's resource goals. However policy constraints effective on different tunnel paths, across different parts of a traffic engineered network may conflict against each other's resource optimization goals.
The policy constraints may trigger continuous re-routing of RSVP-TE & GMPLS-RSVP-TE signaled dynamic tunnels using the principle of ‘Make-Before-Break’ to satisfy the policy goals, even when there is no physical or logical faults in the traffic engineering network. The continuous re-routing of dynamic RSVP-TE & GMPLS-RSVP-TE signaled tunnels through the TE network constitute tunnel flaps, which is not desirable.
The continuous re-routing of MPLS & GMPLS tunnels due to policy applications may generate significant amount of processing overhead on the TE node's control plane and also consume Link B/W resources competing against the resources meant for SLA agreed customer traffic. The present MPLS/GMPLS based traffic engineered transport services deployed in the industry mostly uses policy based re-optimization of tunnels that is either triggered by IGP-TE advertisements of TE Link resources or a periodic timer expiry based.
The re-optimization is achieved via constrained path re-computation and tunnel re-route along the new path using ‘Make-before-break’ method of re-signaling the tunnels. Frequent re-routing (i.e. Tunnel Flapping) due to conflicting impact of multiple different re-route policies applied across different parts of the network is not monitored and also not prevented.
The present state-of-the-art traffic engineering re-optimization is based on the IGP-TE re-advertisement of TE-Link resources and application of network policies and per-Tunnel policies at the origin of the Tunnel. The impact of frequent Tunnel re-routing (Tunnel Flapping) under policy based re-optimization is not considered in evaluating the performance, reliability and availability of MPLS/GMPLS tunnel services. The impact of Tunnel flapping is also not considered in evaluating the availability and effective utilization of TE-Link resources in the traffic engineered networks.